Dynamic compass



March 2 1943. I JEAN-LEON RELITTER DYNAMIC COMPAS S Filed Jan. 3, 1940 2Sheets-Sheet 1 I CWT/POL IVETEE m VI wn UTE N 5 m WM W v -RYMQ%#Z1ADYNAMIC COMPAS S Filed Jan. 3, 1940v 2 Sheets-Sheet 2 m ie.4.

INyEN TOR I JEAN LEON REUTTER By%%w 4 ATTORNEYS Patented Mar. 2, 1943DYNAMIC COMPASS J ean-Lon Reutter, Paris, France; vested in the AlienProperty Custodian Application January 3, 1940, Serial No. 312,220

In France January 4, 1939 Claims. (Cl. 33 222) The present invention,relates to compasses comprising, in combination, a magnetic needleoscillating on a pivot, generally vertical, and means for ensuring themaintenance of its oscillations by impulses imparted to the needle at apoint located in the immediate vicinity of the lubbers point of thecompass; but whereas in compasses of this type already known, theorientation of this lubbers point was deducted from the comparisonbetween the periods of oscillation of the magnetic needle on the onehand, and of a nonmagnetic rocking unit on the other hand, on thecontrary, the invention determines the orientation (or a change oforientation) by the comparison between the relative durations of the twohalf-oscillations of the magnetic needle. It is in fact to be noted thatthese two half-oscillations are of equal duration when the lubbers pointcoincides with the magnetic North- South position, and that thereby, thesustaining impulses are imparted to the needle when the latter is set inthe direction of the terrestrial magnetic field; but that this is nolonger the case when the lubbers point departs from the magneticmeridian, the difierence between the two half-oscillations being so muchthe greater as the angle formed between the lubbers point and themagnetic meridian is itself greater.

The comparison between the durations of the two half-oscillations can beeffected by any me chanical, electric or pneumatic control device forinstance; it is however to be noted that the energy for the control istaken not from the magnetic needle, but from the members which maintainits movement. Thus, any desirable energy can be obtained mechanically orelectrically without modifying the mean position of the needle.Accessorily, it will be noted that the invention eliminates alldifficulties due to the friction of the pivots and to the necessity ofproviding a system for damping the oscillations of the needle in theusual compasses.

The invention can take the form of a number of embodiments, which itobviously includes in its scope and which can differ from each other inparticular by:

The means used for maintaining the movement of the magnetic needle.

2-The means used for controlling said movement and for deductingtherefrom the North- South direction.

The means for maintaining the oscillations can be mechanical, electricor pneumatic. All known mechanical escapements can be used, thespiralbalance wheel system being replaced by the magneticneedle-magnetic field system. The power actuating the escapement can beof any origin whatever. The direct electric maintenance of theoscillations can, according to the invention, take place by superposing,at regular intervals, and at the suitable instant, an electromagneticfield to the terrestrial field, by means of a coil arranged in thevicinity of the magnetic needle. These means will be describedhereinafter.

The pneumatic maintenance can be effected either by the pneumaticwinding-up of a spring driving a mechanical escapement, or by the directaction of an air jet on a wheel provided with fins rigid with the shaftof the escapement wheel, or again, by the direct action of an airjet ona blade rigid with the shaft of the oscillating magnetic needle. r I

Devices in accordance with the invention will be described hereinafter,which constitute entirely mechanical, electric or pneumatic embodiments,but various maintenance methods must be mentioned which, withoutdeparting from the scope of the invention, and generally by a verysimple adaptation, can be combined with the different control methods.

Another particularity of the invention consists in the fact that, if theoscillation period of the needle obviously depends on the intensity ofthe horizontal component of the terrestrial magnetic field, the ratiobetween the durations of the two half-periods from the point ofimpulseis constant for a given amplitude; This remark is important in the caseof a movable object (aeroplane, ship) moving from the poles towards theequator, resulting in a constant increase of the horizontal component ofthe field.

The invention includes in its scope all applications which can be madethereof, but more particularly:

1The application of all the means making it possible to obtain a distanthead indicator and a telecompass.

2-The application of said means to the control of the gyroscope of anautomatic pilot or of an orientation gyroscope.

3The application of said means to the mechanical control of an aeroplanewithout the intervention of a gyroscope.

A diagrammatic description of the various solutions will be givenhereinafter; and as all the members mentioned as well as their functionsare well known to those skilled in the art, a detailed description ofsaid members is hardly necessary.

Referring now specifically to the accompany- .ing drawings forming parthereof,

Fig. 1 illustrates an embodiment of the invention using a mechanicalclock type escapement having a spiral spring.

Fig. 2 is a modification omitting the spring.

Fig. 3 illustrates electrical apparatus embodying the invention in asystem using a double winding to influence a magnetic needle.

Fig. 4 is a modification using a single winding to influence the needle.

Fig. 5 is a detail modification showing how a contact can be used toinfluence the needle, the other portions of the system being omitted tosimplify the view.

Fig. 6a illustrates a pneumatically actuated ap= paratus using a watchtype escapement for oper ating a magnetic needle according to theinvention, while Fig. 6b illustrates a further modifi cation fromanother point of view.

Fig. 7 is a modification showing in part how a pneumatic turbine can bedriven by two air j'ets.

Fig. 8 also illustrates a modification of the pneumatic form of theinvention showing how the magnetic needle may be directly actuated by anair jet.

Fig. 9 is a particular mechanical form of embodiment of the inventionincluding electrical indicator means to carry the indications of thedevice to a distance.

' Mechanical apparatus (Figs. 1 and 2).

In Fig. 1, a magnetic needle I movable about its axis (end view in thefigure) carries a plate pin 2 which receives, as in an ordinary leverescapement, impulses from the fork 3. The latter carries, at the end ofan extension, a wheel 4 meshing with a wheel 5 the axis of rotation ofwhich is in alignment with that of the fork.

For greater clearness, the escapement wheel, the set of wheels whichactuates it, the driving spring and the lever are not shown. In the im'-mediate vicinity of the wheel 4' are provided two driving wheels 6 and lcontinuously rotating in reverse directions to each other, and soarranged that at every rocking movement of the fork 3', the wheel 4comes in contact with one of said wheels 6 or 1 which drives it. Theoperation is consequently as follows:

7 If the pin of plate 2 receives the impulses when the needle I is seton the magnetic meridian a--b, the two half-periods are equal and thewheel 4 is in contact for equal durations with wheel 6 and wheel 1; itwill have a reciprocating movement of very small amplitude, but will notrotate. On the contrary, if the apparatus effects, as a Whole, amovement of rotation about a vertical axis (end view in the figure) andif the position of the magnetic needle at the moment of the impulsebecomes cd instead of ab, the contact of the wheel 4 with the wheels 6and I will be of unequal duration, and the wheel 4 will have, as well aswheel 5 a movement of rotation in a definite direction which would bereversed if the mean position of the needle became e-f instead of 0-11.This movement of rotation will last as long as cd or e-f are differentfrom a-b. This indication can be put in evidence by an index 8 movingover a dial 9.

This apparatus is a simple indicator of the heading when a spiral springlfl is added to the wheel 5, said spring tending to restore the index '8to the zero of the dial. The spiral spring 10 introduces a balance forlever 3 with respect to wheel 5, the lever being taken as normallyvertical and one end ofthe spring connected to the pivot shaft of theleverand the other end to' the wheel so that it forms a very resilientcore nection between said lever and wheel.

Hence, during the interval occupied by the wheel 4 to pass from contactwith wheel G to that with wheel I, the spiral, or, spring 10, if thereis a deviation of index or pointer 8, tends to cause the latter to goback towards ll and the more energetically as the deviation is greater.The rotation of index 8 is limited to a certain value which measures thevariation or divergence relatively to the head initially chosen byadjusting or shifting the device as a whole, and for which the index wasat zero. In Fig. 2, the spiral spring has been done away with, wheel 5meshes with a wheel ii, meshing in its turn with a toothed Crown wheelI2. This crown wheel is assumed to be connected to the movable object(aeroplane or ship) whereas the unit constituted by members I to Ii ismovable about a vertical axis passing through the centre of the wheel 5.In this case, the rotation of wheel 5 would determine, relatively to themovable object, the rotation of the entire device in such a directionthat the magnetic needle i will gradually return to the positionnorth-south, which would cause the ratation to cease. A real compass isthereby obtained the indications of which can be transmitted to adistance by a contrivance such as a Bowden cable, transmission byendless wire, etc.

Electric apparatus In Fig. 3, 20 illustrates a magnetic needle carryinga contact 2! and electrically connected to the body of the apparatus bya spiral spring 22. In the vicinity of 2| are arranged two electrodes 23and 24 which, at each half-oscillation come alternately in contact with2!, thus alternately closing the circuit of the two coil windings 25 and26 of a relay having current reversing contacts 21, through two coils orwindings 2B and 29 adapted to create about the magnetic needle 20alternately, a west-east and an east-west field the function of which isto maintain the movement of the needle 20. The device is supplied by anysource whatever of direct current 35).

The contacts of relay 2! reverse at every halfperiod the direction ofthe current from the source 3! into the polarized amperemeter 32, sochosen that its movable unit has a rather great inertia and a period ofoscillation of its own, which is rapid relatively to that of themagnetic needle. A large capacity 33 .can beadded to the terminals. 7 a

If the contact of 2| with 23 and '24 takes place in the neutral orcentral position of the needle, the relay closes its contacts for equaldurations in one direction as well as in the other, and the polarizedamper'emeter remains at zero. On the contrary, it deviates in onedirection or in the other if, after the whole system has rotated (themean position of the needle remaining fixed in space) the twohalf-periods, that is to say "the durations of the closing of thecontacts of the relay one direction or in .the other, are no longerequal. The ampere'ineter thus becomes a head indicator, its deviationbeing function of the angular divergence from the chosen direction.

This index 34 can in its tum, owing to the presence of the contacts and35, close the circuit of a follow up motor 31 having two directions ofrotation which, by means of a worm 38 formstance, and of a wheel 39 onthe shaft of which the entire system is assumed to be mounted, willbring back the latter to theposition north-south, thus constituting acompass.

The amperemeter 32' can be located at any distance. from the remainderof the apparatus and constitutes a distant head indicator. As regardsthe telecompass, it can be obtained by transmitting to a distance, byany one of the known methods, the position of the wheel 39. In thisform, the coils 28 and 29 and the three contacts 2|, 23 and 24 togetherreplace the gears and pinions of Figs. 1 and 2 and form the electricalequivalent thereof. As already intimated, when the needle swings ineither direction, it closes the circuit of one of the coils 28, 29 andalso that of either one or the other corresponding portion 25 or 26 ofthe solenoid 25 and thereby correspondingly shifts the relay core 26' tothe left or the right so as to shift the one or the other direction andconsequent corresponding operation of worm gear 39 and its shaft-toreadjust and restore the apparatus to zero position with respect toneedle 26.

The diagram of Fig. 4, which shows a modification of thatof Fig. 3, andserves substantially the same purpose as the system of said Fig. 3, canalso be contemplated for maintaining the movement, which allows use of asingle contact on the magnetic needle and a single winding 41, the

contacts 40 and 4E close the circuit of the electromagnet 42 whichactuates the cam wheel 43 through the medium of a pawl and a ratchetwheel. At each impulse, the contacts 44 reverse the current of theamperemeter 45, and maintain desired movement of the needle, whereas thecontact 46 only closes the circuit of the winding 41 once in twohalf-oscillations of the needle.

The desired movement of the needle according to the invention can alsobe maintained by using the asymmetry of'the contact between the needle50 and the tongue 5| according to the partial view of Fig. 5. The restof the system can resemble Fig. 3. The effect of the current can beannulled during the contact 11 by providing that, foran angle the needleis parallel to the magnetic axis MM of a winding. (not shown), whereasfor the angle a of the contact different from there is necessarily adriving torque exerted on the needle. This axis of the winding will formwith the longitudinal axis of the needle at the dead centre, an angle Inthis form, which is also electrical, the gears and pinions of Figs. 1and 2 are replaced by the contacts 40, 4|, the solenoid 42 and the coil41 and their circuits, etc.

Pneumatic Apparatus (Fig. 6), or as indicated in the drawings, Figs. 6a.and 6b show a pneumatically operated escapement in this form whichfunctions as the oscillating means in contrast with the gears andpinions of the first figure.

In this figure, the needle is actuated by using air jet 60 whichdirectly actuates a paddle-wheel 6i rigid with an escapement wheel 62.The fork of the escapement carries on its extension a blade 63 whichalternately intercepts two air jets 64 and 65 placed opposite twonozzles 66 and 6'! each connected to a manometric capsule 68 and 69 by atube of small cross-section. At each oscillation of the fork, the blade63 alternately intercepts for measurable periods of time the air jets 64and 65. If these periods of time are equal, both capsules 68 and 69exert equal stresses on the index 10, and the latter remains inequilibrium. If, on the contrary, these periods of time are unequal, itis obvious that the index 10 will indicate a certain deviation and canserve as head indicator.

The nozzles 86 and 61 causing the desired operation or oscillation ofthe needle can be replaced by a small turbine or bladed wheel ll, Fig.7, which rotates in one direction or in the other according to therelative periods of time it is subjected to the jets 64 and 65. Thenumber of revolutions effected by said wheel transmitted by the worm l2and worm wheel 73, for instance, can be indicated by an index and serveas an indicator. The rotation of the paddle-wheel can be used forcausing the entire device to rotate about a vertical axis due to thepresence of the worm l2 and the worm wheel 13 and for restoring it tothe north-south position, thus providing means serving as a compass.

The swinging or oscillating movement of the magnetic needle according tothe invention (Fig. 8) can also be directly maintained by an air jetwithout the intervention of an escapement. The needle 8E3 carries anextension 8! at the end of which pivots a blade 82 about an axisparallelto that of the needle. This blade carries two arms 83 and 84 the ends ofwhich come in contact with a fixed cam 85 of such a shape that everytime the blade passes in front of the air jet 86 it assumes a positionwhich allows it to receive an impulse in the suitable direction. A pin81 rigid with the needle actuates a fork 88 carrying a blade 85 thefunction of which is exactly the same as that of blade 63 (Fig. 6).

By way of constructional example, the description of a distant or remoteobservation head indicator according to the invention, of particularlysimple construction, will now be given.

A magnetic needle I 00 (Fig. 9) is also maintained in desiredoscillation by a lever escapement the cogs It'll and H32 of which aremetallic, the lever itself being made of insulating material. The powerdriving the escapement wheel, also metallic, can be of any kind, and mayinclude a spring with a set of wheels similar to that of a watch.

The teeth l0! and I02 are each electrically connected by a spiral orflexible wire m3 and H14, to a member Hi5 and I06 insulated from thebody of the apparatus. By the action of the escapement, the currentpasses alternately through one or the other cog in the circuit of whichare respectively inserted the windings, in reverse direction, of apolarized milliamperemeter I01. According to the invention, the periodsof rest equal or different on the cogs will leave the milliamperemeterat zero or will cause it to indicate a deviation as soon as the headchosen, is no longer followed. A single electric cell I08 is sufiicient,and a resistance I09 of a few hundred ohms is inserted in the circuit.Of course, amperemeters of various responsiveness can be inserted in thecircuit.

While Figs. '7 and 8 show modifications or simplifications of thepneumatic operation replacing V the gear and pinion. operation of. Figs.1 or 2, in Fig. 9, the gears and pinions. are replaced by anelectromechanical escapement which in this form serves to produce thedesired oscillation of the needle.

The known art devices, such. as magnetostriction, variation of magneticpermeability, photo-electric cell, variation of frequency of highfrequency or low frequency .circuits, can be used for maintaining theoscillation of the magnetic bar, and for controlling the movement ofthe-needle.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a dynamic compass having anoscill'ating pivoted magnetic needleand actuating means imparting alternately and opposite driving impulsesthereto at two points equally. spaced, at opposite sides of the meanposition of said needle, the combination of indicating means showing theorientation or changes of orientation of a movable support or craftcarrying said compass, follow up control means for controlling saidindicating means including a control member rigidly associated with themagnetic needle at one side intermediate the ends thereof, operatingmeans disposed adjacent to said control member efiective tocorrespondingly influence the actuating means according to theoscillations of said needle and impart any difference occurring betweenthe durations of the opposite oscillations imparted to the needle oneither side of its position of rest when said latter position varieswith respect to the mean position of the operating means.

2. Dynamic compass according to claim 1, wherein the control memberincludes an arm angularly rigid with the needle, and the operating meansincludes a rocking fork actuating said arm, the arm and the pivot ofsaid needle being located on a line coinciding with the mean position ofa fork when the needle is on the lubers point.

3. Dynamic compass according to claim 1, wherein the control memberincludes an arm angularly rigid with the needle, and the operating meansincludes a rocking fork actuating said arm, the arm and the pivot ofsaid needle being located. on a line coinciding with the mean positionof' a fork when the needle. isv on. the. lubbers point or a north andsouth position, and. wherein a freely journalled pinion mounted upon theend of the fork opposite the needle, two spaced driving pinions, andmeans for constantly rotating the same in opposite. directions saidmeansbeing located symmetrically with respect to the. mean position ofthe fork so that oscillation of the. fork will cause alternateengagement of the pinion thereon with the spaced driving pinions andimpart opposite rotary impulses to said pinion upon said fork, and agear concentric with the axis of rotation of said fork meshing with thelast. men.- tioned pinion, having means. for imparting the algebraic sumof the rotations to said last mentioned pinion being transmitted to theindicating means.

4. Dynamic compass according to claim 1, wherein the operating meansinclude electrical means for producing an alternating magnetic fieldwith two spaced contacts, while the control member includes meansassociated with the needle capable of alternately closing said contacts:in order to energize said magnetic field accordingly, and the indicatingmeans including electric apparatus of the polarized ammeter type, therelative location of said magnetic field and said contacts with respectto the needle causing the relative durations of the closing of saidcontacts to depend on the mean position of the needle with respect tothe lubbers point.

5. Dynamic compass according to claim 1, wherein the operating meansincludes a movable member imparting oscillations to the needle, twoopposed supply means for fluid under pressure, means operativelyassociated with said movable member for controlling said supply meansand causing the latter alternately to actuate the indicating means, andmeans associated with said operating means causing said indicating meansto have a difierential operation and to be capable .of operation by saidfluid supply means.

JEAN -LEON REU'I'TER.

